In continuing our studies on the toxicities and ultraviolet absorption characteristics of esters of vanillic and related acids, it was desired to investigate the substituted cinnamic acids related to vanillin. These cinnamic acids are easilyprepared by condensation of the desired aldehyde with malonic acid in the presence of a trace of piperidine with pyridine as a solvent, in accordance with the Doebner modification of the Perkin reaction. The actual procedure employed in this study is an adaptation of the above reaction made by Vorsatz (1) for the preparation of cinnamic acids having a free phenolic group, and is recommended by Johnson (2) for the preparation of ferulic acid. The Vorsatz adaptation employs long standing at room temperature instead of the short boiling originally used by Doebner (3). We have found this modification to be equally satisfactory for the preparation of nonphenolic cinnamic acids. In this study cinnamic acids were prepared from the following aldehydes: vanillin, veratraldehyde, 5-nitrovaniIlin, 5-chlorovanilIin, o-benzylvanillin, piperonal, and orthovanillin. Only in the case of the 5-nitrovanillin was heating necessary to obtain reaction. The reaction of orthovanillin with malonic acid in the Vorsatz procedure yielded a crystalline compound melting at 119-120°, the structure of which was not ascertained, but which yielded orthoferulic acid when boiled with alkali or when allowed to stand for an extended period. No trace of a coumarin or coumarincarboxylic acid was obtained.These acids were esterified with anhydrous ethanol in the presence of sulfuric acid to give good yields of the ethyl esters. Data for the acid and the ester preparations are found in Table I (references to earlier preparations are included). The inhibiting concentrations of the esters were determined for the four representative aerobic microorganisms-namely, non-sporeforming-(Aerobacter aerogenes) and sporeforming-(Bacillus mycoides) bacteria and molds (Aspergillus

Reaction of vanillin, 5-propenylvanillin and 5-allylvanillin with cupric oxide and alkali under conditions of lignosulfonate oxidations yielded only monoguaiacyl compounds. Reaction of the bis-vanillyl compounds, vanillil, vanilloin, desoxyvanilloin, hydrovanilloin and bivanillyi under the same conditions yielded vanillil, vanillovanilione, vanillin, vanillic acid, dehydrodivanillin and others. Thus, the occurrence of many of the compounds in lignosulfonate-cupric oxide reaction mixtures can be accounted for on the basis of a bis-vanillyl structure for a portion of the lignin molecule.

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Alkali lignin was prepared from a commercial, concentrated, skimmed black liquor from the kraft pulping of mixed southern pines. Preliminary oxidation experiments, including alkaline cupric oxide oxidations at atmospheric and superatmospheric pressures, alkali fusions alone and in the presence of peroxides, sodium borate perhydrate, monopersulfate compounds, and sodium sulfide, and similar reactions under pressure gave various phenolic compounds, but in all cases the yields of ether-soluble compounds were relatively low, and much of the original lignin was undegraded. When alkaline solutions of lignin at 170°-180°C. were subjected to gaseous oxygen in 200 p.s.i.g. increments until 600 p.s.i.g. oxygen had been added, about 80% of the lignin decomposed. Fractionating the products yielded oxalic acid and phthalic acid as two of the chief oxidation products. Between 1940 and 1960, in connection with our continuing studies on the oxidation of lignosulfonates, alkali lignins were subjected to various processes for producing guaiacyl compounds such as vanillin, vanillic acid, etc. In many instances the alkali lignin gave oxidation products similar both in kind and in quantity to those obtained under analogous conditions from lignosulfonates. This demonstrated amenability of alkali lignin to oxidation reactions together with an expressed interest in lignin utilization by many alkaline pulp producers led us in 1961 to initiate an industry-wide, group-sponsored research program on oxidizing alkali lignin to monomole-145 Downloaded by MICHIGAN STATE UNIV on February 19, 2015 |